Winter progress

Submitted by Andrea
on January 2, 2012

Due to some prior commitments, Eli pulled his crew from our job for much of November and December, and the pace of our construction slowed down accordingly. Eli already had a busy year lined up when we first called him last spring, but he couldn't resist the lure of building southern Vermont's first (almost) Passive House. He was able to pull it off thanks to a lot of schedule-shuffling, and once we were weathered in it was our turn to be shuffled.

Fortunately, I am such a sporadic blogger that I still have heaps of photos to share. And things are swinging back into high gear, so there should be more rapid and dramatic progress soon.

Let the photos commence! Our solar panels went up in November — 3.96 kW of DC goodness. We're not hooked up yet, but that will happen by the end of this month.

The plumbing work began — I suspect a lot of rough plumbing looks like something drawn by M.C. Escher, but ours is pretty over-the-top:

With Eli's team off in Guilford, we hired a pair of building pros to put up our exterior polyiso (rigid foam) insulation , housewrap, and strapping. We probably won't put up the siding until spring, which means our house will have that classy Typar look for several months. Eli once mused that they ought to sell housewrap printed to look like painted clapboards, but that most Vermonters would then never bother putting up real siding on top of it. I concur.

Anyway, here's the polyiso going up the north wall:

I am pleased to report that Ted's collarbone surgery was a success and that he is recovering nicely. This means that he is back in the DIY saddle, and for the last week we've been busy constructing the two loft spaces.

Ted at the chopsaw:

Before sharing the photos, I should explain the two loft spaces. We haven't built any of the upstairs interior walls yet, because we want to install the ceiling drywall all at once, creating a nice uninterrupted vapor-barrier. But we can't put up drywall until the roof insulation goes in, and it's hard to do any of that with a ceiling that's 25 feet high in spots (above the staircase and the two-story dining area).

Ted and I therefore decided to build the two loft platforms — one is a utility loft over the upstairs office area (it will house the PV inverter and the heat recovery ventilator), and the other is a cozy space we've dubbed the "manatee cave." Ted and I are inordinately fond of manatees (especially dwarf land manatees), and we thought that a manatee cave was much more original than a mere man-cave.

Anyway, here's the upstairs before we started building the lofts:

And here it is afterward:

The manatee cave is on the left, and in the foreground you can see the utility loft. Today we built a temporary platform connecting the two lofts (to facilitate the insulation and drywall work), and tomorrow we plan to build a platform between the utility loft and the west wall, which is where the curved staircase will go (the current staircase is merely temporary).

This last photo won't be very exciting to anyone but a building science geek, but it is very exciting to us. It's the readout from our first blower-door test, taken in December. A blower-door test quickly measures how much a house leaks. If Ted and I want to achieve Passivhaus certification, we need to build an insanely tight house (0.6 air exchanges per hour when pressurized to 50 pascals, roughly equivalent to 0.04 air exchanges per hour in a non-pressurized house).

We had no intention of running a blower-door test this early, because we haven't begun to seal the obvious leaks. The walls and roof are already very tight, but we can still see daylight at the window corners, and the exterior subfloor is completely absent (we need to finish the rough plumbing and electrical work first). But we wanted to insulate the roof so we could put up the ceiling drywall and build the interior walls, so we arranged a preliminary blower-door test to check for leaks around the roof (much harder to fix once the insulation is in). We taped over some of the gaping leak points to prevent them from wrecking the test altogether, but otherwise we haven't done any post-construction sealing.

We weren't expecting a result anywhere near the Passivhaus requirement. So we were quite happily gobsmacked to discover we're very nearly there:

The readout shows that the pressurized house is leaking at 227 CFM, which in our house converts to 0.65 ACH@50Pa. Which means that before we've even insulated or added the ZIP-sheathing subfloor, we are within spitting distance of the rigorous Passivhaus requirement. The test was run by Bill Hulstrunk of National Fiber, and he said that of the thousands of houses he's tested, this was the tightest house he'd ever seen. I am too superstitious to remove the "Almost" from the name of this website, but things are looking good in that department!

Work is now kicking back into high gear — in the near future we hope to get roof insulation, ceiling drywall, rough electrical wiring, and a garage. Our winter has been largely snow-free, a fortunate circumstance I attribute to Ted's and my purchase of a heavy-duty snowblower and season lift tickets at Stratton and Okemo. So I hope to have lots of thrilling new photos soon.